Jutta E. Escher
Lawrence Livermore National Lab
Louisiana State University
North Carolina State University
Workshop Week 3 Agenda [pdf]
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INT Program INT-17-1a|
Toward Predictive Theories of Nuclear Reactions Across the Isotopic Chart
February 27 - March 31, 2017
Nuclear Reactions: A Symbiosis between Experiment, Theory and Applications
March 13-16, 2017
The purpose of the program is to bring together physicists from the low-energy nuclear structure
and reaction communities to identify avenues for achieving reliable and predictive descriptions of
reactions involving nuclei across the isotopic chart.
Recent years have seen exciting new developments and progress in nuclear reaction theory that
allow us to move towards a description of exotic systems and environments, providing deeper
insights into the dynamics of the nuclear many-body system, and setting the stage for new discoveries. For very light nuclei, remarkable progress has been made with ab initio theories, which
describe the systems from first principles, using realistic interactions. At the same time, an intense
interest in heavier nuclei, aided by the availability of dramatically increased computing power,
has driven new developments in shell-model approaches and density-functional theories. These
structure approaches provide crucial input for reaction descriptions.
Experimental facilities involving radioactive ion beams and dramatically-improved multi-physics
simulation capabilities provide new challenges and opportunities. Nuclear theory must address
phenomena from laboratory experiments to stellar environments, from stable nuclei to weakly-bound and exotic isotopes. Expanding the reach of theory to these regimes requires a comprehensive understanding of the reaction mechanisms involved as well as detailed knowledge of nuclear
structure. A collective effort of the reaction and structure community is essential to address major
open questions about the nature of strongly interacting matter and the origin of the elements.
The program aims to intensify the dialogue and to work towards a better integration of the complementary theory efforts. The embedded workshop specifically intends to integrate experimental
research as well as to take into account needs of the nuclear data community. We will focus on
two essential goals:
Program Format and Topics
Determine strategies for expanding current ab initio nuclear structure and reaction descriptions towards medium-mass nuclei;
Determine strategies for moving towards microscopic theories of heavy nuclei to achieve
increasingly more predictive descriptions of the structure and reactions of heavy nuclei.
We will follow the standard format of daily talks of the participants, supplemented by informal
afternoon meetings. In addition there will be overview talks in the focus areas. The program will
focus on the following key topics:
Integrated structure and reaction ab initio modeling: Addressing the challenge
of heavier nuclei, continuum, and multiple reaction channels.
Ab initio approaches carry predictive power, which is critical for studying short-lived isotopes inaccessible by experiment, but are currently limited to light nuclei. Following the
development of ab initio structure models that exhibit a better scaling, the program will
discuss and guide the development of ab initio reaction theory for medium-mass nuclei.
Effective interactions in reaction calculations.
Effective interactions (optical potentials) have to enter reaction descriptions when possible
reaction channels are eliminated from explicit consideration. The program will address the
challenge of developing effective interactions that have predictive power in the regime of
exotic nuclei, where data is scarce, and seek strategies for anchoring these interaction in ab initio, microscopic, or effective theories.
Improving structure inputs to reaction approaches.
To achieve more reliable predictions for unstable nuclei, it is important that ab initio theories
inform/replace current microscopic models for medium-mass systems, while microscopic
methods need to replace the phenomenology used for heavier systems. The program will
review recent developments in nuclear structure theory and identify avenues for integrating
improved structure information into new and existing reaction theories and codes.
Integrating relevant reaction processes into a coherent framework.
For reactions involving the lightest of elements, a truly integrated structure and reaction
description is being achieved, while for medium mass and heavy systems this remains to
be done. The program will discuss the interplay between various reaction processes (direct,
semi-direct, pre-equilibrium, and compound reactions) and consider options for developing
descriptions that treat these processes in a better integrated manner.
Overall, we expect this program to provide a clearer picture of the capabilities and gaps of the
theory, as well as strategies for moving forward. We anticipate our conclusions to be informed
by (existing and anticipated) experimental capabilities and marked by an awareness of the data
needs of inter-disciplinary efforts, e.g. in astrophysics.
Workshop Format and Topic
The workshop Nuclear Reactions: A Symbiosis between Experiment, Theory and Applications
will be coordinated by J. Blackmon (LSU), N. Scielzo (LLNL), and J. Escher (LLNL).
This workshop is dedicated to the intersection of experiment, theory, and applications. It will focus
on connecting theory developments to experimental advances and data needs for astrophysics and
A workshop format will be adopted with a series of talks (overview as well as specific) each day
and opportunities for discussions. The presentations will cover experimental needs and capabilities
and outline the needs of the astrophysics and nuclear data communities. Discussions will aim at
identifying gaps in existing theories and identify possible experimental tests of current and planned
theories. Focus areas will be explored where (future) experimental work can provide benchmark
results that make it possible to compare different theoretical methods and test their reliability.
We also plan to identify immediate applications of new theoretical developments, e.g. reaction
measurements at radioactive beam facilities.
There will be a $40 registration fee to attend the workshop. The registration fee includes participation in the workshop, lectures, and coffee breaks.